Outboard motors are often powered by internal combustion engines. The engine is typically positioned within an enclosed cowling. The engine is generally vertically arranged, so that a crankshaft thereof may extend downwardly in driving relation with a water propulsion device of the motor, such as a propeller. In order to balance the motor and because of space considerations, the engine is arranged with a crankcase of the engine facing in the direction of a watercraft to which the motor is mounted, and with the cylinder head and intake system positioned on an end of the engine facing away from the watercraft.
Air must be supplied to the engine through the cowling for combustion. An air vent is provided in the cowling. Due to the orientation of the engine, a surge tank of the engine's intake system is positioned on the end of the engine facing the watercraft.
In order to prevent the direct entry of water through the vent into the intake system, the vent must be positioned away from the intake system. Thus, the vent is typically positioned in the portion of the cowling above the cylinder head of the engine (i.e., above the end of the engine opposite the surge tank). Air is drawn through the vent along the top of the engine to its front end and into the intake system.
A problem arises in that air within the cowling is heated by the engine and rises upwardly and mixes with the incoming fresh air. The engine thus draws a mixture of fresh and heated engine air, resulting in poor engine performance.
A cowling arrangement for an outboard motor which permits the engine therein to draw fresh air and which prevents the entry of water into the intake system, is desired.